Mary-Kate Olsen recently stepped out in NYC with a giant ring on that finger, adding fuel to the engagement speculation that has been surrounding the 27-year-old designer and her French banker beau, Olivier Sarkozy.

But if they lovebirds are ready to say "I do," it seems that the pair is still on a different timeline with regards to how soon the twosome plan to tie the knot.

E! News has learned the former actress wants to "marry and settle down as quickly as possible," while Olivier wants a "nice long engagement."

"If they are engaged, they haven't announced it to family and friends in France yet, but who knows," an impeccably placed source in Olivier's home city of Paris tells us.

"All we know is that Olivier will want a nice long engagement—he's been through a marriage already and had lovely kids, so he knows what it's all about," the source revealed.

Sarkozy and ex -wife Charlotte Bernard split in 2010 after 13 years together. The former couple has two children, son Julien, 12, and daughter Margot, 10.

Another topic of concern for the couple? The place where they plan to build their life together if they do indeed want to settle down.

"They haven't been in Paris for a while," the insider said of the duo. "It looks like the ring is an American one, which would make sense as Mary-Kate always seems a lot happier in the states." The loved-up pair was most recently spotted packing on the PDA—yet again—while watching a New York Knicks game at Madison Square Garden in mid-December.

"Paris is all about Olivier's old life—his wife included," the insider continued. "America is all about his new life with Mary-Kate. She's always made it pretty clear that she wants to settle down as quickly as possible."

In January, the couple visited some of Paris' ancient churches, prompting speculation they were checking out marriage venues.

But Olivier is since said to have played down the idea of a Paris wedding, and wants to "keep the whole thing on the other side of the Atlantic," said the source.

And while their engagement has yet to be confirmed, the insider added that if a proposal did occur "it would have been during a recent holiday they spent in Jamaica."

Olivier is the half-brother of Nicolas Sarkozy, the former president of France, whose third wife is former supermodel-turned-pop singer Carla Bruni.

Asked if Olivier and Mary-Kate plan to meet up with the famous couple in New York, where Carla is due to perform next month, the source replied: "No—they're all very busy people."

In addition to the engagement buzz, there have also been reports in the U.S. which claim Mary-Kate would be happy to have a baby with Olivier without being married to him, but friends of Olivier in Paris said they knew nothing of the tabloid claims.